Alarm protection



Aug. 3 1926. 1,594,817

' F. E. CRAWFORD ALARM PROTECTION 'Original Filed Angus; 12 1921 Patented Aug. 3, 1926.

. y 1,594,817 sur carica,

FRANKLIN E. CRAWFORD, F VVINCHESTER, MASSACIJI'SEI'JLTS, ASSIGNOR TO BATKERS ELECTRIC PROTECTIVE ASSOCIATION, QF BOSTON, MASSACHUSETTS, AV CORPORA- TION OF MASSACHUSETTS.

Anania PROTECTION.

Application led August 12,1921, Serial` No. 491,803. Renewed .Tune 19, 1925.v

My invention relates to protective devices for safety vaults and the like, oit the class characterized by the employmento't an electric-protection layer, normally in circuit with sound or other alarm devices, which on being punctured 0r otherwise deranged produces an abnormal condition in Y the alarm circuit, and automatically gives notice that it has been disturbed by some intrusive agency.

Such electro-alarm layers, surrounding or lininfr the vault space are practically a sate- Y guard against unannounced mechanical penetration, in almost any conceivable emer- *5 ygency; ibut it is possible forV a Vhighly skilled expert, provided he knows or can accurately estimate the thickness of the steel or other,

exterior sheathingwhich lies next to the electro-protective layer, to drill carefully o and by inicrometric measurement exactly through the thickness oit' such sheathing` Without penetrating or;` otherwise disturbing,r the normal condition Ot the electroprotective or electro-alarm layer` and thus to expose the said layer by cuttingr out a panel of the sheathing. It isfurtlier pos'- sible, though extremely difficult, so totanal per with the electric connections of the electro-alarm layer as to permit its dis. placement Without causing it to give an alarm.

Though the diiiiculties opposed to the successful penetration of a safety vault protected in the manner above brieiiy described' are so many and so great that no 'failure of well installed protective devices of the character indicated to ,qive notice ot an at-4 tempt to break into the vault has been known or reported to me; yet, tlie aim of vault protective measures is to guard against the reinotest possibility oic failure, and to concede to skilled safe-breakers the posses-y sion of consumate skill and resource. The object of this invention is to render it'impossible to expose or even to penetrate to the electro-alarm layer ota vault protecty ing enclosure, Without so deranging` its structure as to cause an alarm to be given.

Mechanical tools and instruments of precision, in the hands of an adept, can be limited in their range of action,-depth of cut and penetration into materials, With ,creat accuracy. But the penetration, conduction, and diffusion of heat is beyond such control. The basis of my invention is the establishment of conditions exterior to an electrdalarm layer: which encloses a safety vault or tlie'lile such that heat'must` e applied to the covering or sheathing in such a Way asI to derange' an element or elements of the electro-alarm layer, before" the covering or sheathinga can bepenetiated by a. mechanical tool, such as a drill. l

Further, my invention has Vfor its object not only the protection of the contents'of the sate or vault, but the essential structure of the safe or vault itself.` This structure, especially in modern installations,` is often very costly, and damage to it is a serious item, even though the contents of the saife or vault be not reached. :Therefore in the preferred Ytorni, my invention affords protection to the safeor vault itself, by prof i viding an external sheathing or casing, which surrounds or overl'ies the main struc# ture, and is relatively inexpensive to, in-

stall, or toi-estore it damaged, and'whi'ch comprises a covering of tool-resistingP material'in such proximity to an electro-alarm layer or sheathing inside that heat'applied to deg-rade, destroy or penetrate the toolresisting;` material Will also derange an elenient or elements of the alarm-layer. The electro-alarm sheathing, as usually l constructed,` comprisesone or more layers of thin, loyv 4 melting .inetal,l such as tinseparated lby an electrically inlayer, forr yexample paper, coated or saturated With shellac. electro-alarm layer is therefore heat` sensitive, as Well as susceptible to puncture by mechanical means. Heat disintegrates or` traverses the 4insulation and sottens one `or more ofthe conducting elements, ot the electro-alarm layer', `and, establishes a short circuit certain to cause an alarm. In carrying out my invention herein {de-V scribed, 'any electro-alarm layer susceptible to deranpgement by heat of its normal elec trical relationship with the alarm system of which it constitutes a part, may be ein-Y ployed. i

In the drawings hereto annexed, Which diagrainmatically illustrate my one embodiment of my invention, by Wayof example," Figure 1 represents,` in section, the ele-` ments of the, protective devices; and shows diagramniatically one type of alarm system The which may be used in connection with the improved protective covering and Fig. 2, in section, the saidy devices applied to the exterior ofA the safe or vault structure. V

Fig. 3 is a detail yof a portion of Fig. l showing switch B in released position; and

Fig. 4f is a modification of the .construction ot' Fig. 2, showing the protective layers spaced apart trom the vault proper.

In Fig. l, E represents the electro-alarm layer as a Whole, and C and I rep-resent the inductive and vinsulating laminas, respectively, of a typical heat sensitive electro-alarm layer, S `the interior casing of a vault chamber, and P that portion of the exterior sheathing which lies Ioutside and next to the electro-alarm layer. I employ the term layer .or sheathing .as indicative of a structure Vdisposed lgenerally parallel to the .surface .of the safe or vault and Without reference to the specic character or dimensions of such structure. .since it may consist .of imperforate, foraminous, kor reticulated sheet material of any `desired -thickness of it may l.consist merely of one -or vmore ilaments, stri-ps, or sections of suitable material. VThe exterior sheathing P maybe, for example, a. laminated steel plate, of ivhich P', P fare 4sheets of mild steel, and P2., P2 sheets of hardened, vtoolresisting chrome steel, which will, successfully resist `the attack of any practicable drill -or other penetrating tool.

The experienced safe breaker, on discovering that 'the plate P-comprisesftool-resisting steel, ivi-ll be constrained to nemploy heat to dranT the temper of, or degrade .the steel, or in the alternative to relinquish his object.

When heat is applied locally tothe plate Pfor this purpose 'by the use, for example, of the 'Oxy-acetylene flame it will eventually reach the elements 0 I, With the result that the normal structure of the electroalarm elements is vvderanged and short circuits, thus giving notice vthat a break is being attempted. Y

It will be understood, that While the plate P. is shown in the drawing as `theonly 'structure exterior to :the electro-alarm layer., it may be overlaid -vvith other materials. For the purpose of carrying out this invention,

the .tool-resisting sheathing is and need be exterior only -to the electro-alarm layer. Preferably, though not necessarily, it will be placed 4next to the electro-alarm layer, the essential :being that the tool-resisting Vportions of the protective sheet shall be so related to the deformable or destructible, i. e., heat sensitive, element or elements vof the A electro-alarm layer, that a thermal agency,

high to cause derangement thereof and coni sequently sounding of the alarm. In the preferred form of my invention, the tool-resisting sheathing P, with electroalarm sheathing associated with it, as above described, Will be placed Wholly exterior to the essentials of the sate or vault str cture, so that an alarm will be given when the tool resisting member of these protective devices is subjected to, heat, and therefore before the essential and usually costly sate or vault structure can have been dan'iagel. A vault door for instance, is not infrequently the point loi" yattacx; my composite protective sheathing, is secured to the exterior ot a vault door., Will it attacked by a. safe breaker, give the alarm before any .portion of the door lis damaged except the relativeh.v inexpensive i sheathing, and the complicated and costly mechanism Within the vault-door structure will remain unharmed. In F 2, S represents generally part of the vaultstructure, be it the door or a Wall, and I?, the `composite `protective layer shown more inA detail i-n Fig. 1. A moditication ot the same is shownl in Fig. 4:, wherein the coniposite protective layer P is constructed outside of and spaced apart 'fromthc vault structure S.

In order to prevent lthe exterior sheathing from being bodily yremoved from the electroalarm layer Without giving an alarm, additional yalarm means may be provided tor this purpose. Thismeans is preferably associated with the electro-alarm layer so as lto utilize the same alarm. Thus in Fig. l I have shown circuit-closing means arranged to close the circuit between the electro-ala rm layers `C when the sheathing P is removed, this means comprising an insulating base .ik mounted in a .re-cess in plate S. a circuit closer B mounted on the base A and an actuator D depending from the circuit-elena? into contact With inner .plate P. The Aends of circuit-closer -B are bent outwardly through openings in the base A and .layers I and C, Aone lend normally contacting with the. inner layer Cand the other end contacting ivi-th the :other layer C in response to the elasticity lof that circuit-closer when the actuator D is disengaged by the inner plate P upon the removal `of the latter'.

lhile the electroprotective layer E has herein been shown as ycomprising a pair ot normally insulated electrical conductors C intended vto form elements of a normally open electrical circuit, it is lmanifestly clear that it a closed circuit alarm ysystem were employed, a single kone only of such conducting elements would be necessary, the destruction of such element under the action Yof heat serving to give the alarm, Likewise in an vopen circuit -system',`one of the conducting elements 'C might Well be dispensed with, since the Tyall of the safe or vault, if of metal, or theprotective layer P could act as one of the conductors of the circuit, and upon breaking down of the insulating material interposed between such metal part and the conductor C va shortcircuit would be formed which would give the alarm in the same mannerv as though the two conduct rs C Were provided.`

In Figui, Iliave illustrated diagrammatically one :torni of alarm circuit which may be' employed in connection `vvith this protective covering. This alarm circui't comprises Wires X, Y connected respectively to the conductor elements C. IThese Wires X, Y may be connected to any suitable alarm, for example a bell Z,-a battery-W or other suitable source of electrical energy being interposed in one oie these Wires. This alarm circuit is of the open circuit `type and is closed to give the signal by short circuiting of the conductors C With each other. This particular alarm circuit is merely illustrative ot Vany type of alarm circuit which may be `:tound suitable for the purpose whether such circuit be of the open or closed type.

l/Vhat I claim, and desire to secure by Letters Patent is:

Y l. In combination With a vault or sate,` an outerV protectiveL covering therefor com-V prising a pair ot members constitutingl elements ot an alarm circuit, means easily disintegrated by heat normally insulating said members, and a layer ot material substantially impenetrable to mechanical agencies arranged in heat conducting relation to one at least of said members and serving to protect said members and the insulating means from mechanical injury.

2. In combination with a vault or sate, an outer protective covering therefor comprising a pair of relatively insulated sheets of metal constituting elements of an electrical alarm circuit, said metallic sheets and the insulating material being or a character such that the plates are readily short circuited upon the application of heat, and a plate ot tool resistant material overlying said sheets of metal with their insulation and in heat conducting relation thereto, said plate serving to prevent tamperwith said metallic sheets.

3, ln combination with a vault or safe, an outer protective covering therefor comprising sheets ot metal of low melting point separated by a thin layer ot insulation easily destroyed byheat, said layers constituting elements ot an electrical alarm system, and a. layer or" material exterior to said sheets ot metal tor protecting the latter from mechanical injury.

a. ln combination with a vault or safe, a protective coveringI applicable thereto, said covering comprising an insulated layer ot material forming an element of electrical material, and means carriedby said covering normally operative to prevent contact of said arm with theother layer'ot' material but permitting such contact upon bodily separation of the covering from the vault or sai'e.

6. An outer protective covering applicable to `a vault or sate, said covering comprising at least one electrical conductor forming an element otV an alarm circuit, means normally insulating said electrical conductor, and protective materialsubstan-l tially impenetrable to mechanical agencies disposed outwardly of said'covering'vvith respect to the conductor to protect the "latter from mechanical injury, the lconductor being 'of a character such that it is deranged by the application of heat and being so disposed relatively to said'protective material that a thermal agency of suiiicient intensity to destroy the protective properties of the latter, when applied to such protective material, will also derange the conductor.

7. In combination with a vault or safe, a layer of material substantially impervious to mechanical agencies disposed adjacent and in protective relation to the outer surtace of the vault or: safe, and an alarm circuit comprising an electrical conductor disposed at the inner side of said layer of mechanically imperviousV material, said conductor being of a material such that it may be destroyed by the application of heat, the conductor being electrically insulated and so related to the aforesaid layer of mechanically impervious material that when the latter is subjected to a thermal agency of suflicient intensity to degrade or penetrate it, the conductor Will likewise be destroyed.

8. An outer protective covering for a vault or sate comprising atleast one electrical insulated conductor constituting an element of an alarm circuit, means normally insulating said conductor, said insulating means being of such character as to lose its insulating qualities when subjected to heat, and protective vmaterial substantially impenetrable to mechanical agencies so disposed as to protect the insulating means and the electrical conductor from mechanical injury, said insulated conductor when the protective covering is in operative position, be-

ing disposed adjacent to another conducting part also forming an element of the alarm circuit, said protective material being so disposed relatively to said insulating material that when a thermal agency of sullicient intensity is applied to the protectiye mate rial to degrade or penetrate the latter, the heat :trom said agency Will break down the insulating material thereby permitting contact of said normally insulated conductor With said other conducting part. f

9. The combination with a vault or safe ot an alarm circuit, a protective covering for the vault or safe, said covering comprising at least one fusible electrical conductor constituting an element of the alarm circuit, means i'or insulating said conductor,

said insulating means being :of a characterk such that it breaks down Whenfsubjected to heat and being so disposed with relation to the protective material that when ,the latter is subjected to Vthe action of .a thermal agency ot suflicient intensity ,to destroy its protective qualities the heat oit said thermal agency will also break Vdoivn` the insulating "means and fuse the conductor.

10. An outer protective covering for a vaultror safe comprising at least one insulating conductorV normally constituting one element yofy an alarm icircuit, and protective material substantially impenetrable lto mechanical agencies so disposed relatively tothe conductor asV toy protect 'the latter from injury, said protective material being so lrelated Ito the conductor Athat when .subjected tok .a thermal agency .of suicient in* tensity to destroy its protective qualities the conductor will likewise be deranged by the heat of said thermal agency.

111. An outer protective covering for a vault orsafe comprising a vpair of easily fusible conducting elements of an alarm circuit, insulating material easily Vdisintegrated by heat normally insulating -said -con ductors from one another, and a layer of material substantially impenetrable to mechanical agencies in heat conducting relation to said insulating material and con ducting elements and serving .to protect `said insulating material and conducting elements from mechanical injury.

l2. In combination with .a vault or sate an outer protective covering therefor `comprising a layer of insulating material easily disintegrated by heat, .an kalarm circuit including at least one relatively easily fusible conducting element Within and insulated by said insulating layer, and a layer of niaterial .substantially vimpenetrable to mechanical agencies in heat conducting relation .to said insulating layer and ,conducting 4ele- Vment and serving to protect said insulating 'layer and conducting element from mechan-v ical injury, said protective covering being co-eXtensive with the area to be protected.

Signed by'me at Boston, Massachusetts,

i this 3rd day of August, 1921.

FRANKLIN E. CRAWFORD. 

